Gamma camera with light guide having greater index of refraction

Abstract

A gamma camera comprises a scintillation crystal having an index of refraction of 1.80-190, a collimator for imaging the object on one face of the scintillation crystal, an array of photodetectors arranged around the opposite face of the scintillation crystal, and a light guide interposed between the opposite face of the scintillation crystal and the plurality of photodetectors. The light guide is selected to have an index of refraction of at least 1.60, higher than in the conventional gamma camera, whereupon it has been found that the detection efficiency and the positional accuracy of each scintillation event can be increased, to thereby increase the sensitivity and the spatial resolution of the gamma camera.

What is claimed is: 
     
       1. A gamma camera including a scintillation crystal, a collimator for transferring a gamma-ray image to one face of the crystal, a plurality of photomultiplier tubes arrayed at the opposite face of said crystal for receiving the light photons emitted by the crystal as a result of the absorption thereby of gamma rays, and a transparent light guide interposed between said opposite face of the crystal and said photomultiplier tubes, said crystal having an index of refraction of 1.80-1.90, and said light guide having an index of refraction of at least 1.60. 
     
     
       2. The gamma camera of claim 1. wherein the index of refraction of the scintillation crystal is 1.84, and the index of refraction of the light guide is from 1.6 to 1.7. 
     
     
       3. The gamma camera according to claim 1, wherein the index of refraction of the light guide is greater than that of the scintillation crystal. 
     
     
       4. The gamma camera according to claim 3, wherein the index of refraction of the scintillation crystal is 1.84, and the index of refraction of the light guide is 1.95. 
     
     
       5. The gamma camera according to claim 1, wherein said light guide is bonded to said scintillation crystal by glue having an index of refraction approximately equal to that of said light guide. 
     
     
       6. The gamma camera according to claim 1, wherein the surface of said light guide adjacent to said photoconductor is roughened. 
     
     
       7. A gamma camera according to claim 1 wherein the index of refraction of said light guide is uniform in the direction defined by said collimator. 
     
     
       8. A gamma camera according to claim 7 wherein the index of refraction of said light guide is uniform throughout. 
     
     
       9. A gamma camera according to each of claim 2 wherein the index of refraction of said light guide is uniform in the direction by said collimator. 
     
     
       10. A gamma camera according to claim 3 wherein the index of refraction of said light guide is uniform.